FIG. 1 represents a typical mine ventilation layout with airflow control equipment. The intent is not to generalize the FIG. 1 layout example to all mines, but to typically explain and associate the optimized mine ventilation system application to mining ventilation. The optimized mine ventilation system can be applied to an infinite variation of mine layout configurations.
As shown on FIG. 1 a mine is typically composed of the following elements:
One or more intake fans [FIG. 1, element (2)] provide air from the surface atmosphere to the underground infrastructure via one or more downcast shafts [FIG. 1, element (3)]. The fans speed is manually controlled by a local controller or by a basic control system with surface HMI (Human Machine Interface). The control system usually also includes startup and shutdown sequences and protection interlocks.
The downcast shaft(s) provides fresh air to working levels where production occurs on one or more extraction zones off each level [FIG. 1, elements (5, 6, 7)]. Ramps with or without access doors will also divert some air from each levels to other levels [FIG. 1, elements (8, 9)]. Ramps provide a route for equipment to move from one level to another.
Ore and waste material is extracted from the production zones by diesel machinery and is dropped in ore or waste passes down to lower levels to be crushed and brought back to the surface by conveyors in shafts [FIG. 1, elements (26, 27)].
Air is forced from each level to the ore extraction zones or service areas [FIG. 1, elements (10, 11, 29, 12, 13, 14)] by auxiliary fans and ducting connected to the fans [FIG. 1, elements (15, 16, 30, 17, 18, 19)]. As per the surface fans, the auxiliary fans speed is manually controlled by a local controller or by a basic control system with surface HMI (Human Machine Interface). The diesel particulate emission contaminated air from the ore extraction zones comes back to the level via the ore extraction excavation.
Contaminated air is flowing to upcast shaft(s) [FIG. 1, element (4)] through fixed opening bulkheads or bulkheads with variable air flow regulators [FIG. 1, elements (23, 24, 25)]. The air flow regulators position is manually controlled by a local controller or by a basic control system with surface HMI (Human Machine Interface).
In some modern installations air flow measurement stations are found at the bulkhead [FIG. 1, elements (20, 21, 22)].
Sometimes when the surface fans capacity is exceeded, lower levels will have additional booster fans used as in-line pressure enhancers [FIG. 1, element (28)]. The fans speed is manually controlled by a local controller or by a basic control system with surface HMI (Human Machine Interface). The control system usually also includes startup and shutdown sequences and protection interlocks.
One or more exhaust fans [FIG. 1, element (1)] draw air from one or more upcast shafts [FIG. 1, element (4)] out to the surface atmosphere. The fans speed is manually controlled by a local controller or by a basic control system with surface HMI (Human Machine Interface). The control system usually also includes startup and shutdown sequences and protection interlocks.
Traditionally the calculation of required setpoints for fans speed and bulkheads surface area opening or air flow regulator opening position has been achieved by manual survey results of air flows and regulatory requirements for maximum diesel equipment presence in one work zone. In addition, numerous mine operators use the calculation assistance of commercially available ventilation network steady state non real-time simulators designed to simulate existing ventilation networks. Fan operating points, airflow quantities, and frictional pressure drops are obtained from those calculations to assist derive physical operating setpoints.
There are several drawbacks and deficiencies in those fans speed and bulkhead opening setpoint calculations:
Surveys are spontaneous measurements and are not representative of the changing operating environment of a live mine. Therefore, maximum safe setpoint values have to be used to be representative of the worst case scenarios.
Commercially available simulators lack one or more of the following capabilities rendering them unfit for live real-time control. They are either non real-time calculation engines unfit for live control. Their pressure and flow calculations may also omit the depth air column compensation for air density and pressure calculation which creates significant errors in the results also rendering them unfit for live real-time control. Their flow calculations may not be compensated for natural ventilation pressure flows from temperature differences. This also renders them unfit for live real-time control.
The aforementioned control equipment setpoint calculation methods are therefore used with limits and safety factors that cannot dynamically adjust to accommodate a live diesel machinery ventilation presence often wasting valuable air therefore not available to other work zones. Hence, those setpoint calculations do not offer a live dynamic optimization of the air flow routing and distribution. In conclusion, those production ventilation setpoint calculation methods often prohibits mine operators to access deep remote ore body sectors due to the lack of available air.
The optimized mine ventilation system has been engineered to circumvent those previously mentioned setpoint calculation deficiencies. The optimized mine ventilation system permits on-demand ventilation as per dynamic personnel location and dynamic diesel machinery location and operating status. An optimized zonal ventilation demand is calculated and the optimized mine ventilation system assures optimal air routing and distribution at minimum energy cost.
The optimized mine ventilation system does not require costly air flow sensors which typically have proven problem prone installations due to the harsh mine air environment. Routine maintenance of those sensors is therefore eliminated. Only a few sensors will be required to keep a live correlation check with the model.